An electrochemical cell is a device capable of either deriving electrical energy from chemical reactions or facilitating chemical reactions through the introduction of electrical energy. Electrochemical cells are integral components of electrochemical sensors, which utilize electrodes to produce a current that is related to a detected amount of a molecular species allowing for the measurement of the concentration of the molecular species (e.g., gas or aerosolized substance) in a mixture of fluids (e.g., in air). Electrochemical sensors/cells can be incorporated in devices that measure environmental pollutants, such carbon monoxide detectors, and may also be used to measure breath alcohol. Because they require very little power to operate, electrochemical sensors/cells have been widely used in personal safety devices that measure toxic gases.
Plastic welding by laser or adhesive has been done previously with metal wire vias or planar printed electrical contacts to seal electrochemical cells. Also, layer-by-layer assembly of plastics with preformed adhesives has been done, where high temperature processes like platinum activation or printed electronic ink curing are done first, followed by electrolyte addition and sealing. Generally in electrochemical gas cells the working electrodes, and in planar schemes, all electrodes, are close to the gas inlet (e.g., located on a lid with a gas permeable membrane aperture). Several designs and processes address plastic-to-plastic assembly and provide in-plane electrical connections, but are typically unsuitable for integration of heterogeneous cell materials (e.g., glass-to-plastic, etc.) and provide electrical contacts near the top (gas inlet) side in the planar case, or through the sidewall in the case of metal wires. There is a need in the art for similar or dissimilar electrochemical cell materials, especially incorporating planar electrodes, to be attached robustly and sealed with a minimal bond width and sidewall thickness and in a manner that allows for electrical connections (vias) to the bottom side (opposite the gas inlet), so as to have an upward facing gas inlet and bottom side electrical connections suitable for connecting via a plug connector or low temperature die attach to an electrical circuit or printed circuit board. In such an arrangement the gas inlet is facing away from the PCB, a desirable orientation for common applications requiring an input aperture in a cover case or for incorporation of special gas filters that would be challenging or impractical if the filter had to be on the same side as the electrical connections. Electrochemical cell materials with high rigidity that can be processed into highly anisotropic features including reservoir cavities and vias are also desirable for minimizing the overall size of the cell.